Trump has frequently criticized the agreement, saying it does not address Iran's ballistic-missile program and its role in conflicts in Yemen and Syria, its nuclear activities beyond 2025, and the terms under which international inspectors can visit suspect Iranian nuclear sites.

“At the conclusion of the wind-down periods, the applicable sanctions will come back into full effect,” the statement said.

A statement issued by the State Department said that as Washington exits the Iran deal, it will be working with allies to “find a real and comprehensive” solution to the “Iranian threat.”

“As we build this global effort, sanctions will go into full effect and will remind the Iranian regime of the diplomatic and economic isolation that results from its reckless and malign activity,” the statement said.

In Tehran, President Hassan Rohani swiftly responded to Trump’s announcement, saying Tehran is ready to resume its nuclear work after holding talks with European Union signatories of the deal.

"If negotiations fail, the Islamic republic will enrich uranium more than before...in the next weeks," Rohani said a televised speech.

"I have ordered Iran's atomic organization that whenever it is needed, we will start enriching uranium more than before," he said.

Earlier on May 8, Rohani acknowledged Iran could "face some problems" if Trump announced that he will reimpose sanctions on the country.

Rohani said "It is possible that we will face some problems for two or three months, but we will pass through this."

Rohani said on May 7 that Iran would remain in the nuclear accord even if the United States withdraws, on the condition that the other parties -- France, Britain, China, Russia, and Germany -- stick with the agreement.

The leaders of France, Germany, and Britain said on May 8 that they were committed to implementing the Iran deal despite Trump's decision to pull out and his threat of sanctions.

In a joint statement, British Prime Minister Theresa May, German Chancellor Angela Merkel, and French President Emmanuel Macron they “will work with all the remaining parties to the deal to ensure this remains the case including through ensuring the continuing economic benefits to the Iranian people that are linked to the agreement.”

They urged the United States to refrain from taking action that prevents other signatories to the Iran nuclear deal from continuing to implement it.

Macron's office said the French president spoke in the evening on May 8 with Merkel and May about the Iran accord and next steps after Trump's decision.

Macron said that France, Germany, and Britain regretted Trump's decision to withdraw from the nuclear deal.

"The nuclear nonproliferation regime is at stake," he wrote on Twitter.

"We will work collectively on a broader framework, covering nuclear activity, the post-2025 period, ballistic activity, and stability in the Middle East, notably Syria, Yemen, and Iraq," he added.

European Union foreign police chief Federica Mogherini said the EU “is determined to preserve” the deal, which she described as “one of the biggest achievements diplomacy has ever delivered.”

“We expect the rest of the international community to continue to do its part, to guarantee that it continues to be fully implemented for the sake of our own collective security,” Mogherini said on May 8.

The Russian Foreign Ministry criticized Trump’s announcement, calling it a “disguise to settle political accounts with Iran.”

Former U.S. President Barack Obama, whose administration brokered the deal with Iran, called Trump's decision "misguided" and "a serious mistake," especially because Iran has been complying with the agreement.

"The consistent flouting of agreements that our country is a party to risks eroding America's credibility, and puts us at odds with the world's major powers."

Saudi Arabia, a regional rival of Iran, welcomed Trump’s decision to withdraw from what it described as a “flawed agreement.”

"Iran used economic gains from the lifting of sanctions to continue its activities to destabilize the region, particularly by developing ballistic missiles and supporting terrorist groups in the region," according to a Saudi Foreign Ministry statement.

Israeli Prime Minister Benjamin Netanyahu expressed strong support for what he described as Trump's "bold" decision “to reject the disastrous nuclear deal with the terrorist regime in Tehran.”

On April 30, Netanyahu unveiled tens of thousands of intelligence documents that he said showed Iran's secret nuclear weapons ambitions.

Trump referred to those documents in his speech announcing the withdrawal.

Iran says its nuclear program is entirely peaceful and its compliance with the deal has been verified by the International Atomic Energy Agency.